1. Field of the Invention
The invention relates to silane-modified polyvinyl alcohol mixtures and their use in paper coating slips.
2. Background Art
Polyvinyl alcohols are used as cobinders in paper coating slips in order to improve the gloss and the brightness of the paper coating. The paper coats, in particular for inkjet papers, are exposed to a high mechanical load. It is therefore necessary for the coatings to be characterized by high abrasion resistance. Moreover, the formulation must ensure good ink absorption without the ink drop running or spreading.
EP-A 76940 describes silicon-containing polyvinyl alcohols which are used for paper coating. The silicon content is introduced either by subsequent silylation of polyvinyl alcohol or by means of copolymerization of ethylenically unsaturated, silane-containing comonomers with vinylestermonomers, and subsequent hydrolysis of the vinyl ester units.
EP-A 1127706 discloses paper coatings which are characterized by high water resistance, light stability, and heat stability, and are therefore quite suitable for use outdoors. This property profile is obtained by a combination of pigment, silanol-modified polyvinyl alcohol, and a film-forming polymer having a Tg<50° C.
Heat-sensitive recording papers having a coating which contains silicon compounds are disclosed in DE-C 3519575. The silicon compounds may be silicon-modified polyvinyl alcohol in combination with colloidal silica and/or amorphous silica.
EP-A 1080940 discloses a coating composition for the production of heat-sensitive recording materials or inkjet papers which contain ethylene/vinyl alcohol copolymers, silicon-modified vinyl alcohol polymers, or silicon-modified ethylene/vinyl alcohol polymers as one component, and an organotitanium compound as a further component.